Inhibitory Effect of Certain Chemical Food Preservatives against Cercospora Leaf Spot Disease of Sugar Beet

Abstract

The antifungal activity of citric acid and its salt (sodium citrate) as chemical food preservatives was evaluated against Cercospora beticola in vitro and in vivo. The inhibitory effect of both compounds was studied against mycelial growth of the pathogen in vitro at concentrations, i.e. 0, 10, 20, 30, 40 and 50 mM. Both of citric acid and sodium citrate were able to inhibit the mycelial growth of the pathogen when they were added to the medium at the tested concentrations. Citric acid at 50 mM had the highest effect on the inhibition growth of the pathogen being 83.70% and also had antifungal activity. The percentage of inhibition growth increased as the tested compounds concentration increased. Data also indicate that microscopic examination of treated plates with citrate shows that this treatment reduced the numbers of C. beticola spores on the medium at all tested concentrations and reached its maximum reducing at concentration 50 mM of citric acid compared to untreated plates. The results revealed that spraying of diseased plants with citric acid and sodium citrate either alone or in combination at concentration 50 mM was effective in decreasing disease severity of Cercospora leaf spot compared to untreated plants. The highest reduction in disease severity was observed in case of citric acid treatment. The results revealed that foliar application of these compounds enhanced significantly root yield and sugar percentage as compared to the control.

Impact of pre and post-harvest treatment with chemicals preservatives on Botrytis gray rot disease and fruit quality of strawberry

“…The roles of food additives are protecting the product from microbial contamination and prolong the shelf life of the product; to ensure the safety of products. Benzoic acid, sodium benzoate, citric acid, sodium citrate and potassium citrate are used as chemical preservatives to enhance the shelf life of food, because they have a high ability to inhibit a wide range of microorganisms (Blaszyk and Holley, 1998;El-Fawy, 2018). Some mechanisms have been suggested to explain the inhibitory effect of these chemicals on microorganisms.…”

“…Citric acid inhibits the growth of proteolytic Clostridium botulinum due to its Ca+2 chelating activity (Graham and Lund 1986). Several studies also mentioned the role of citrate in control of many plant diseases (Abdel-Monaim and Ismail, 2010;El-Fawy, 2018;Mohamed et al, 2015). The food additives such as potassium sorbate and sodium benzoate had antifungal activities against postharvest decaying fungi (Al-Zaemey et al, 1993;Olivier et al, 1999).…”